Registration for the Chicago Marathon has been postponed until March 19 so organizers can “finalize a routine yet comprehensive assessment of our new registration process,” according to an announcement on the race’s website.

The change came after registration for the 2013 edition had to be stopped on opening day, February 19, 2013, because of technical problems. Demand for the race’s 40,000 available spots overloaded the Active.com registration system, and registration was suspended after three hours.

The lottery was scheduled to be open from Wednesday, March 5 and close April 7. It will now open at 12 p.m. Central Time on March 19 and remain open until 12 p.m. April. 7.

“We apologize for this inconvenience and thank you for your patience and understanding as we aim to ensure a seamless registration experience for all who wish to register for the event,” the statement on the website read.

Participants will be notified for their selection status on Monday, April 14.